JP2001213336A - Electric hydraulic power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unify a hydraulic pump and an electric motor for miniaturization, and to substantially eliminate the necessity of disassembling and maintenance. SOLUTION: In this electric hydraulic power steering device for assisting the steering force with the hydraulic pressure of a hydraulic driven by an electric motor, a brush-less DC motor is used as the electric motor, and a pump body of the hydraulic pump is integrally formed with a nearly cylindrical motor case part projected toward the electric motor. The stator of the electric motor wound with a field coil is fixed to the motor case part, and a wiring board of the field coil arranged at a hydraulic pump side of a permanent magnet rotor of the electric motor, and an encoder is arranged at an opening side of the motor case part, and the opening of the motor case is sealed with an cover plate. Since the rotor is formed of the permanent magnet and the stator is formed of the field coil, a necessity of manufacturing the motor case of steel or the magnetic material is eliminated, and magnetization of the stator becomes unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric hydraulic power steering apparatus used for reducing the steering force of an automobile or the like by the hydraulic pressure of a hydraulic pump driven by an electric motor.

[0002]

2. Description of the Related Art A power steering apparatus widely used in automobiles and the like uses hydraulic pressure generated by driving a hydraulic pump by an engine. That is, during operation of the engine, the hydraulic pump is constantly driven, and when the hydraulic pressure exceeds the set pressure, the hydraulic pressure is kept constant by the relief valve.

In this case, it is necessary to set a pump capacity, a relief valve, and the like so that a set pressure can be obtained even during a low-speed operation of the engine such as during idling. For this reason, especially at the time of high-speed operation, the amount of oil released by the relief valve increases, and there is a problem that the efficiency decreases.

Then, a hydraulic pump is driven by an electric motor,
An electro-hydraulic power steering (Electro-Hydraulic Power Steering) device that obtains a steering assist force using the hydraulic pressure generated by the hydraulic pump has been proposed and is already used. This device electronically controls the rotation speed and torque of a hydraulic pump drive motor based on signals from a vehicle speed sensor, a steering angle sensor, and the like.

Conventionally, a DC motor with a brush has been combined with a hydraulic pump. For example, a motor having a shunt characteristic using a permanent magnet as a field (stator) instead of a field coil has been used.

[0006]

In such a DC motor with a brush, a permanent magnet is used as a magnetic field. Therefore, a case for accommodating the magnetic field needs to be made of a material (iron or magnetic material) through which a magnetic flux passes. Therefore, when the case of the hydraulic pump is made of an aluminum alloy or the like, it is necessary to make this field case separately.

The field of the brushed DC motor is magnetized by a special magnetizing machine after a magnet material in a non-magnetized state (not magnetized) is fixed to the case. It must be a case that can be mounted on the machine.
Generally, a pump body (pump case) of a hydraulic pump is provided with a member for mounting on a vehicle body, an oil strainer, and a connection portion for connecting an oil tube to a steering gear box. In order to be able to attach the magnetizer to the magnetizer, the magnetizer must be modified.

For this reason, conventionally, the motor case is made of iron or a magnetic material separately from the case of a hydraulic pump made of aluminum alloy or the like, and the motor case is mounted on a magnetizing machine as a separate body from the pump body. The motor case is made easy to magnetize, and the magnet material is fixed to the motor case and then magnetized.

For this reason, there has been a problem that the hydraulic pump and the electric motor cannot be integrated with each other, resulting in an increase in the overall size. Further, the DC motor with a brush needs to be disassembled for maintenance of the brush, so that it is required to improve disassembly and maintainability.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to integrate a hydraulic pump and an electric motor, to reduce the size of the whole, and to eliminate the need for disassembly and maintenance. It is an object to provide an electric hydraulic power steering device.

[0011]

According to the present invention, an object of the present invention is to provide an electro-hydraulic power steering apparatus for assisting a steering force by a hydraulic pressure of a hydraulic pump driven by an electric motor, wherein the electric motor is a brushless DC motor, A pump body of the pump is integrally formed with a motor case portion protruding in a substantially cylindrical shape toward the electric motor,
A stator around which the field coil of the electric motor is wound is fixed to the motor case, and a wiring board of the field coil is disposed on the hydraulic pump side with the permanent magnet rotor of the electric motor interposed therebetween, and an opening side of the motor case. And a motor-driven power steering apparatus characterized in that an encoder is disposed in each of the motor cases and an opening of the motor case is closed by a cover plate.

That is, by using a permanent magnet for the rotor (rotor) and a field coil for the stator (stator), the motor case does not need to be made of iron or magnetic material, and the body of the hydraulic pump is made of aluminum alloy. The stator is fixed to the motor case so as not to be magnetized.

Since the pump body is extended so as to surround the stator (stator) of the motor, a substantially box-shaped circuit case having a sufficient capacity extending substantially over the entire length of the pump body is formed on the side surface of the pump body. It becomes possible to do. Therefore, a sufficiently large circuit board can be accommodated in the circuit case.

For example, a main switching circuit and a motor control circuit necessary for controlling the field current can be mounted on the circuit board. In this case, the main switching circuit and the motor control circuit can be mounted on a common circuit board, which is suitable for miniaturization.

The main switching circuit is preferably arranged on the hydraulic pump side of the board, and the motor control circuit is preferably arranged on the motor case side. In this case, the main switching circuit that generates a large amount of heat approaches the hydraulic pump side, but the oil (power steering oil and hydraulic operating oil) circulates in the pump body of the hydraulic pump, so that the temperature of the oil is reduced. It is stable and the cooling performance of the main switching circuit is improved.

In particular, the main switching element group of the main switching circuit is mounted on the surface of the circuit board facing the pump body, and these main switching element groups come into close contact with the pump body when the circuit board is mounted on the circuit case. By doing so, the cooling performance of the main switching element is improved. That is, the pump body is used as a heat sink of the main switching element.

In this case, the main switching element may be directly adhered to the pump body. However, the main switching element group is fixed in a flat and thin substantially dish-shaped case to form a module, and this module is adhered to the pump body. You may make it. The case used for modularization is preferably made of a metal such as aluminum to improve thermal conductivity.

It is preferable to provide a window hole facing the main switching circuit and the motor control circuit in the motor case, and to connect the wiring board of the field coil and the circuit board through the window hole. In this case, the field coil and the main switching element are connected in the shortest distance, so that the wiring is simplified and the generation of electromagnetic wave noise to the surroundings can be reduced.

At this time, the wiring board of the field coil and the circuit board can be connected to each other by a connector passing through a window, so that the circuit board is simultaneously connected to the wiring board by the connector when the circuit board is loaded into the circuit case. Then, the connection between the wiring board and the circuit board can be performed with one touch, and the assembling property is improved. As a connector used here, for example, a Faston terminal (product name) is suitable.

Since a field current flowing through the field coil flows through the wiring passing through the window, it is necessary to provide a current detector for detecting the field current near a position facing the window on the circuit board. Good. The window hole communicates the inside of the motor case with the circuit case. The motor case can be sealed by sealing the circuit case.

[0021]

FIG. 1 is a conceptual diagram of an electro-hydraulic power steering device according to the present invention, FIG. 2 is a sectional view of a main part thereof, and FIG.
Is a sectional view taken along line III-III showing the inside of the circuit case, and FIG. 4 is a bottom view in which the lid is partially cut away.

In FIG. 1, reference numeral 10 denotes a steering gear box, in which a power cylinder for generating an assist force, a control valve, a rack-and-pinion type steering gear, and the like are incorporated. The rotation of the steering wheel 12 is transmitted to the steering gear box 10 via a universal joint, and moves the tie rods 14, 14 connected to both ends of the steering rack in the vehicle width direction. At this time, the control valve controls the flow of oil supplied to the power cylinder according to the steering angle. The tie rods 14, 14 are connected to a knuckle arm of the front steering wheel, and the front wheels are steered by the left and right movements of the tie rods 14, 14.

Reference numeral 16 denotes a hydraulic pump unit. The unit 16 has a DC brushless motor 18, a hydraulic pump 20, and a reservoir tank 22 which are vertically aligned and integrated. That is, the motor 18 is connected to the hydraulic pump 2
A pump tank 24 (FIGS. 2 to 4) is integrally assembled with a lower part of the pump body 24, and a reservoir tank 22 for storing power steering oil is connected to an upper part of the pump body 24. The structure of the hydraulic pump unit 16 will be described later.

The torque and the rotation speed of the motor 18 are commanded by a controller 26 comprising a vehicle control computer different from the unit 16, and the torque and the rotation speed of the motor 18 are controlled based on the command signal. .
That is, the controller 26 includes a steering angle sensor 28,
Based on various traveling data from the vehicle speed sensor 30, the engine speed sensor 32, and the like, an optimum torque and a rotation speed of the motor 18 are calculated and sent to the motor 18 as a command signal. As described later, the motor 18 has a motor control circuit 8 for controlling a field current based on the command signal.
6 and a main switching circuit 84.

The hydraulic pump unit 16 has a substantially cylindrical pump body 24. The inside of the pump body 24 is vertically divided by a partition wall 34, and the upper part thereof serves as a housing space for the hydraulic pump 20. The reservoir tank 22 has a cylindrical shape with the lower part opened, and the lower part is a pump body 24.
Is fitted into the circular upper opening. Therefore, the upper part of the hydraulic pump 20 has entered the reservoir tank 22.

A motor case 36 is integrally formed below the pump body 24. That is, the lower part of the partition wall 34 becomes the motor case part 36. This pump body 2
4 is made, for example, by casting an aluminum alloy.

The motor case 36 has a substantially cylindrical shape opened downward. 3 and 4 on the outer peripheral surface of the motor case portion 36.
A pair of mounting arms 38 projecting horizontally as shown in FIG.
38 are integrally formed. The hydraulic pump unit 16 is fixed to the vehicle body by these mounting arms 38,38.

The circuit case 4 is provided on the side of the pump body 24.
0 is provided. The circuit case 40 extends from the side of the hydraulic pump 20 to the side of the motor case portion 36 and has a substantially box shape extending over substantially the entire length of the pump body 24. The circuit case 40 is formed by overlapping a rectangular frame member 42 and a cover plate 44 on the pump body 24 and bolting them (FIGS. 2 and 4). A seal is interposed between the pump body 24 and the frame member 42 and between the frame member 42 and the cover plate 44 to seal the inside.

Inside the circuit case 40, one circuit board 46 is mounted. The circuit board 46 is screwed to a mounting pedestal formed on the side surface of the pump body 24 shown inside the circuit case 40 (see FIG. 3).

Next, the DC brushless motor 18 will be described. The motor 18 uses a direct current as a power source and rotates a rotor (rotor) 48 having a permanent magnet attached thereto in a stator (stator, field) 52 around which a three-phase field coil 50 is wound. The stator 52 has a large number of magnetic poles formed by winding a field coil 50 through a bobbin 54 on a core on which steel plates are stacked. The rotor 48 is made by magnetizing a permanent magnet material (alnico magnet, ferrite magnet, neodymium / iron / boron magnet, etc.) fixed to a rotor shaft 56 in a magnetizer (not shown).

As shown in FIG. 2, the stator 52 has its outer periphery fixed to the inner peripheral surface of the motor case portion 36 of the pump body 24 by press-fitting or bonding. The rotor 48 is inserted from the lower opening of the motor case 36 along the central axis of the stator 52. The upper part of the rotor shaft 56 passes through the partition wall 34 of the pump body 24 and is supported here by a bearing 58. On the other hand, a lower portion of the rotor shaft 56 is supported by a bearing 62 on an inner surface of a cover plate 60 attached to an opening of the motor case portion 36. The upper end of the rotor shaft 56 enters the hydraulic pump 20,
The hydraulic pump 20 is driven. As the hydraulic pump 20, an appropriate structure such as a vane pump or a gear pump is used.

The terminal of the field coil (winding coil) 50 is
The bobbin 54 is connected to a disc-shaped wiring board 64 fixed to a surface facing the partition wall 34. This wiring board 64
An electric conductor is wired to the power supply to distribute the three-phase field current (winding current) to each phase of the field coil 50. As shown in FIG. 2, three connector terminals 66 (only one is shown) that protrude toward the partition wall 34 and are bent in parallel with the outer diameter direction are fixed to the wiring board 64.

The motor case 36 includes a circuit case 4
0 is provided in the connector terminal 6.
Reference numeral 6 designates the position of the wiring board 64 in the circumferential direction so as to face the window hole 68. On the other hand, three connector sockets 70 (only one is shown) extending from the window hole 68 into the motor case 36 are fixed to the circuit board 46.

The connector socket 70 is connected to the circuit board 4
When fixing 6 in the circuit case 40, it is aligned and connected to the connector terminal 66 on the wiring board 64 side. That is, when the circuit board 46 is fixed, the connector including the connector socket 70 and the connector terminal 66 can be simultaneously connected with one touch, and the assembling workability is good.

An encoder 72 is provided on the opening side of the motor case 36. The encoder 72 has a magnetized disk 74 fixed to the end face on the opening side of the rotor 48, and three Hall elements 78 held on a disk 76 fixed to the bobbin 54. The magnetized disk 74 is magnetized to N and S poles corresponding to the magnetic poles of the rotor 48. Hall element 78 is 1
It is fixed at 20 ° intervals (equal angular intervals) and detects the rotational angle position of the rotor 48.

The detection signals of the Hall elements 78 are transmitted through the window holes 80 provided in the motor case 36 to the circuit board 46.
(FIG. 2). That is, the cover plate 60 of the motor 18
Is opened, a wiring cord (not shown) is first guided from the circuit board 46 through the window hole 80 to the disk 78 side.
This wiring cord is connected to the connector 82 provided on the disk 78. Then, the lid plate 60 may be closed and sealed.

Next, the circuit board 46 will be described. The circuit board 46 is made of, for example, a multilayer printed wiring board, and the window hole 68 faces near the center thereof, and the connector socket 70 enters the motor case portion 36 through the window hole 68. The main switching circuit 84 is mounted in the upper half area of the circuit board 46, that is, in the area on the hydraulic pump 20 side with the connector socket 70 interposed therebetween. A motor control circuit 86 is mounted in a lower half area, that is, an area on the motor 18 side with the connector socket 70 interposed therebetween.

The main switching circuit 84 controls the phase of the field current by turning on and off the field current of each phase at a predetermined phase. For example, a bridge circuit is formed by six FETs (field effect transistors) 88. Is made to form These FETs 88 are mounted on the surface of the circuit board 46 facing the pump body 24 as shown in FIG.
These FETs 88 are covered with a substantially dish-shaped case 90 made of a thin metal plate such as aluminum, and the top surface of each FET 88 is fixed with a resin having good heat conductivity so as to be in close contact with the inner surface of the case 90 to form a module. Is done. FE
Of course, other switching elements, such as a transistor and an IGBT, may be used instead of T88.

When the circuit board 46 is fixed in the circuit case 40, the dish-shaped case 90 is brought into close contact with the side surface of the pump body 24 on the side of the pump 20, thereby improving the heat dissipation of the FET 88. The pump body 24 and the dish-shaped case 90
In between, a double-sided adhesive tape with good heat conductivity is interposed to improve heat transfer.

As shown in FIG. 3, the motor control circuit 86
It has a C element 92 and sends a gate signal for controlling the phase of the field current to each FET 88 of the main switching circuit 84 based on a command signal sent from the controller 26 (FIG. 1). Note that transmission and reception of the drive current of the motor 18 and signals to and from the controller 26 are performed via connectors 94 and 96.

The connector socket 70 is located between the main switching circuit 84 and the motor control circuit 86 as described above. The mounting portion of the connector socket 70 on the circuit board 46 side is a current using a Hall element. A detector 98 is mounted. For example, Hall CT (Current T
ransformer) to detect the two phase field currents.
Individually installed. At this position, the current detector (Hall C
By providing T) 98, the field current wiring can be minimized.

[0042]

According to the first aspect of the present invention, since the motor for driving the hydraulic pump is a DC brushless motor as described above, the motor case does not need to be made of iron or a magnetic material, and the pump body is made of aluminum alloy or the like. When the pump body is made of a non-magnetic material, the motor case can be integrally formed with the pump body. Further, it is possible to fix a stator that does not require a magnetizing process to the motor case. Therefore, unlike a DC motor with a brush for fixing a permanent magnet stator to a motor case, the motor case does not need to be made of iron or a magnetic material, and it is not necessary to magnetize the stator, so that the motor case is integrated with the pump body. It becomes possible to.

As a result, the hydraulic pump and the motor are incorporated in a common pump body to promote integration, and the size of the apparatus can be significantly reduced. DC brushless motors do not have brushes, so maintenance is almost unnecessary.

Since the motor case is integrated with the pump body, the circuit case can be made sufficiently large when the circuit case is integrally provided on the side surface of the pump body. Therefore, it is possible to accommodate not only the motor control circuit, for example, the main switching circuit but also the motor control circuit in this circuit case. Therefore, downsizing of the device can be promoted.

In this case, it is preferable to use a single circuit board and mount a main switching circuit on the hydraulic pump side and a motor control circuit on the motor side. With this configuration, the main switching circuit through which the field current, which is a large current, flows, and the motor control circuit that controls the minute current can be arranged separately, and noise of the main switching circuit adversely affects the motor control circuit. Can be prevented.

In this case, the main switching elements of the main switching circuit are mounted on the surface of the circuit board on the pump body side, and these main switching elements are brought into close contact with the pump body so that heat can be radiated to the pump body. Good (claim 4). Since the power steering oil circulates through the pump body and its temperature is stable, this is used as a heat sink for the main switching element.

To achieve this, a plurality of main switching elements are covered with a flat and thin dish-shaped case and solidified with a resin having good heat conductivity to form a module, and the dish-shaped case is brought into close contact with the pump body to release heat. Is improved (claim 5).

If the connection between the circuit board and the field coil is made as follows, the assembling property is good. That is, the wiring board of the field coil is provided on the hydraulic pump side of the stator, and is connected by a connector passing through a window hole provided in the motor case portion. In this case, the connector can be connected in the mounting direction of the circuit board, and if the connector terminal and the connector socket are fixed to the wiring board and the circuit board, respectively, the connection of the connector is performed with one touch at the same time as the fixing of the circuit board. It becomes possible. For this reason, the assembly efficiency is further improved.

The current detector for detecting the field current is preferably mounted on the circuit board so as to face the window through which the connector passes. This is because the wiring from the main switching circuit to the field coil can be minimized. Although the motor case and the inside of the circuit case communicate with each other through the window hole, if the circuit case is sealed, the motor will be sealed with this circuit case, ensuring the airtightness and waterproofness of the motor. (Claim 8).

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an electric hydraulic power steering device.

FIG. 2 is a cross-sectional view of the main part.

FIG. 3 is a sectional view taken along line III-III showing the inside of the circuit case.

FIG. 4 is a bottom view in which a cover plate of the motor is partially broken.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Steering gear box 16 Hydraulic pump unit 18 DC brushless motor 20 Hydraulic pump 22 Reservoir tank 24 Pump body 36 Motor case part 40 Circuit case 46 Circuit board 48 Rotor 50 Field coil (winding coil) 52 Stator 60 Motor lid plate 64 Field coil wiring board 66 Connector terminal 68 Window hole 70 Connector socket 84 Main switching circuit 86 Motor control circuit 88 Main switching element (FET) 90 Substantially dish-shaped case 92 Current detector (Hall CT)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Kato 1 Morimachi Morimachi, Shuchi-gun, Shizuoka Prefecture 6 Moriyama Industry Co., Ltd. F term (reference)

Claims (8)

[Claims] 1. An electric hydraulic power steering apparatus for assisting a steering force by a hydraulic pressure of a hydraulic pump driven by an electric motor, wherein the electric motor is a brushless DC motor, and a pump body of the hydraulic pump is connected to the electric motor side. A motor case part projecting in a substantially cylindrical shape is integrally formed, while a stator around which a field coil of the electric motor is wound is fixed to the motor case part, and the hydraulic pressure is sandwiched by a permanent magnet rotor of the electric motor. An electro-hydraulic power steering device, wherein a wiring board of a field coil is provided on a pump side, and an encoder is provided on an opening side of the motor case portion, and an opening of the motor case is closed with a cover plate. 2. A substantially box-shaped circuit case extending substantially from the side of the hydraulic pump to the side of the motor case portion over substantially the entire length of the pump body is provided on a side surface of the pump body. The electro-hydraulic power steering apparatus according to claim 1, wherein the board is mounted. And a main switching circuit for controlling a field current at a position on the side of the hydraulic pump on the circuit board, and the main switching circuit at a position on the side of the stator of the circuit board. 3. The electro-hydraulic power steering device according to claim 2, wherein a motor control circuit for controlling is mounted. 4. A plurality of main switching elements forming a main switching circuit are mounted on a surface of the circuit board facing the pump body, and the main switching elements are in close contact with the pump body in a state where the circuit board is mounted on a circuit case. The electric hydraulic power steering apparatus according to claim 3, wherein 5. A plurality of main switching elements are fixed in a flat, thin, substantially dish-shaped case to form a module,
5. The electro-hydraulic power steering device according to claim 4, wherein the module is in close contact with the pump body. 6. A motor case is provided with a window hole facing between the main switching circuit on the circuit board and the motor control circuit, and the wiring board of the magnetic field coil is connected to the circuit board by a connector penetrating the window hole. Electric hydraulic power steering device. 7. The electric hydraulic power steering apparatus according to claim 6, wherein a current detector for detecting a field current is mounted at a position facing the window hole of the circuit board. 8. The circuit case according to claim 2, wherein the circuit case is sealed.
7. The electric hydraulic power steering device according to any of 7.